Our Science – Parkhurst Website
Maria R. Parkhurst, Ph.D.
The mission of the Peptide Synthesis Core Facility is to produce a variety of peptides (generally less than 50 amino acids in length) with sufficient purity for Surgery Branch principal investigators and to identify new tumor-reactive T cell receptors against peptide epitopes for use in gene therapy clinical trials.
Peptide Epitope Identification
Tumor-reactive T lymphocytes specifically recognize and lyse tumor cells based on the binding of a tumor-reactive T cell receptor (TCR) with a specific peptide-major histocompatibility complex (MHC) displayed on the surfaces of tumor cells. Nearly all of the peptides synthesized at this core facility have represented potential T lymphocyte epitopes restricted by either class I or class II MHC molecules derived from tumor-associated proteins. In several recent Surgery Branch clinical trials tumor-reactive TCRs were cloned into retroviral vectors. These vectors were then used to modify genetically non-reactive T lymphocytes and, after transduction, these T cells were able to specifically recognize and lyse tumor cells in vitro. Furthermore, gene-modified T cells expressing tumor-reactive TCRs mediated clinically objective regression of cancer in several patients after adoptive transfer. To extend these studies to patients with different types of cancer, we are working to identify new tumor-reactive TCRs that specifically bind to peptide-MHC complexes on cancer cells. Toward this goal, we have undertaken several studies to identify and clone such TCRs from HLA-A2 transgenic mice. Specifically, these mice were immunized with peptides derived from the human proteins that represent potential tumor-associated antigens, including NY-ESO-1 and carcinoembryonic antigen (CEA). After several rounds of in vitro stimulation, splenocytes from immunized mice specifically recognized human tumors expressing HLA-A2 and the full-length protein. We cloned the reactive TCRs from these splenocytes and introduced them into non-reactive human T cells by means of RNA electroporation. The gene-modified human T lymphocytes then specifically recognized and lysed human tumor cells.
Currently, we are trying to identify similar TCRs that could specifically recognize peptides derived from a candidate antigen overexpressed in tumor vasculature, namely vascular endothelial growth factor receptor 2 (VEGFR2), and from another cancer-testis antigen, preferentially expressed antigen in melanoma (PRAME). In addition, we are currently developing a GMP-quality retrovirus encoding the CEA-reactive receptor for use in a clinical trial similar to the trial described previously.
This page was last updated on 3/4/2013.